Applied Physics

Mokhtar Chmeissani

The focus of the applied physics research at IFAE is to develop sensor technologies with applications in medical imaging, high-energy physics and other scientific or industrial fields by exploting the valuable knowledge available at IFAE and fostering collaborations with other research centres in Catalonia like the Centro Nacional de Microelectronica (CNM), medical centers like Hospital Parc Taulí, or companies like Multiscan Technologies.

Introduction

In 2019, the medical imaging/applied physics group at IFAE has participated actively in several projects: exploiting the potential use of VIP-PET as Compton-PET Scanner, the production of 6cm x 6cm pixel camera for the 3D-Biopsy-Tomosynthesis project , developing adaptive retinal implant, and participating in the design of 12 bits ADC for Timepix4 ASIC.

3D-BONT (3D Biopsy on Tomosynthesis)

The project, funded by RIS3CAT, aims to develop a novel 3D Tomosynthesis breast biopsy system in collaboration with IFAE, Centro Nacional de Microelectronica (CNM-IMB), Hospital Parc Tauli, IDNEO Technologies S.L., and VENTURA Medical Technologies. In 2019 IFAE team concluded the prototype hardware of the full camera as shown in figure 1. To reduce the dead area because represented by back-end of the sensor chip, we opt of designing the motherboard with 4 long baby board (bb) in a form of ladder shape, each bb carries 4 sensors. In this approach the top view show one solid area of 16 sensors. The camera sensor dissipate about 30W and to extract such amount of heat we decided to use cold plate under the bb, made via 3D metal printing device.

Figure 1: Shows on the left the complete box housing the pixel CdTe camera for the biopsy machine. On the right one can see the full biopsy machine and the camera box installed and cabled.

LINDA (X-ray LINe Detector with novel photon counting ASIC)

IFAE has submitted LINDA project proposal and it was selected and funded by ACCIO in June 2019 and funded. The project aims to construct a 20 cm long Spectral X-ray Line Camera in a period of 18 months. The line camera to be mounted, and later tested, in commercial X-ray scanner machine for food quality control. The camera will use the ERICA ASIC which includes a charge summation algorithm (patent granted in China, pending in EU, Japan, and USA), which is fundamental technique, to achieve a spectral X-ray response in a photon counting pixel detector.

Figure 2: It shows the principles of a X-ray line Camera. A single ERICA sensor (1mm thick pixel CdTe bonded to ERICA chip) is shown in the upper right corner. The radiography of the pen has been done using single ERICA sensor. In July 2020 LINDA camera, 20 cm long, made from 30 ERICA sensors will be ready for testing.

LINDA technology from research to industry

In 2019, IFAE participated in the innovation programme of Mobile World Capital (MWC) Barcelona and the LINDA project was selected by the Collider program and this could eventually translate the LINDA project from research prototype to a scaled up industrial product. Bellow one can see the MWC certificate award.

i-Vision (Adaptive Retinal Implant Technology for Vision Restoration)

In 2019 Institut de Física d’Altes Energies (IFAE) and in collaboration with Catalan Institute of Nanoscience and Nanotechnology (ICN2), The Institute of Photonic Sciences (ICFO), Barraquer Foundation (BF), and Paris Vision Institute – Sorbonne Université (PVI) submitted a successful proposal to La Caixa-Health-2019 and the proposal was selected for funding. The project started December 2019 and will last for 3 years. The goal of this project is to develop advanced retinal prosthesis technology capable of providing high-acuity artificial vision to individuals blinded by eye retinitis disease. In such eye disease, neurons responsible for conveying information to the brain remain alive. A retinal prosthesis electrically stimulates these neurons in precise pattern to re-create vision sensation. IFAE is leading the development of a wireless (power and data) retinal prosthesis, patent protected. The duration of the project is for 3 years. At the first stage the retinal prosthesis will be used in vitro and at a later stage it will be implanted in the eye of a pig to test its performance and durability in vivo conditions.

Figure 4: shows schematically an array of electrodes (red color) made of graphene and are sandwiched between an ASIC (blue color) and the top layer of the retina and close to Ganglion cells. An external camera (mounted on a dedicated eyeglasses) captures an image frame and it gets sent to the ASIC wirelessly , via modulated light at high frequency that follow the pattern of data string (…00110001111….) to program each pixel/electrode on the ASIC. The same light is used as well to power the ASIC itself using Photo-Voltaic cell

Figure 5: shows the schematic of the wireless, high acuity, adaptive retinal implant to be developed by IFAE

Medipix4/Timepix4

Medipix4/Timepix4 is the 4th generation of the of Medipix photon counting ASIC. IFAE, as member of the Medipix Collaboration has contributed to the design of Timepix4 chip based on 65 nm CMOS process technology. IFAE contribution is the design and layout of a 12-bits incremental sigma-delta Analogy to Digital Converter (ADC) to monitor 32 different internal voltages of the chip. The integration of the ADC inside the chip will allow to reduce the number of I/O pads as well as to provide a direct digital measure for real time monitoring. Though the ADC is designed for Timepix4, it will be implemented as well in the Medipix4 ASIC. Timepix4 has been tested and early results show it is fully operational.

Figure 6: Shows theTimepix4 wafer before dicing it and having it ready for testing